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118. Formation and structure of active carbons from anisotropic cokes
Abstracts
Both factors exerted their influence below 500°C. Neither factor significantly affected the open micropore volume developed in the chars. 110. Effect of pyrolysis conditions on subsequent gasification of low-temperature lignocellufosic chars D. M. Mackay and P. V. Roberts (Department of Civil Engineering, Stanford
University, Stanford,
CA 94305).
Chars, prepared by pyrolysis of prune pits at I or lS”C/min to 500, 700 or 9OO”C, were subsequently gasified by CO, at 900°C. Pyrolysis conditions did not significantly affect the porosity developed for a given mass loss due specifically to gasification reactions, i.e. excluding additional pyrolytic losses. 111. Porous structure of active carbons and adsorption kinetks A. M. Volochtchouk, M. M. Dubinin and V. A. Gordeeva (Institute of Physical Chemistry of the USSR Academy of Sciences, 117312, Moscow,
U.S.S.R.). New
experimental results on the kinetics of adsorption by microporous active carbons are analyzed using homogeneous and biporous adsorbent models. For some adsorption systems neither homogeneous nor biporous models describe the experimental data obtained properly. Modified biporous model of microporous adsorbents and conditions of the applying of the homogeneous and biporous models of adsorbents are considered. 112. Molecular probe adsorption analysis of actfvated carbons A. Linares-Solano, J. de Lbpez-GonzBlez, J. M. Martin-Martinez and F. Rodriguez-Reinoso (Department of Inorganic Chemistry, University of Granada, Granada, Spain). Two activated carbons, prepared from olive
stones and almond shells, have been reacted with air at 350°C to obtain carbons with a large range of porosity. The adsorption of nitrogen, carbon dioxide, n-butane, benzene, cyclohexane, n-hexane, iso-octane and 2,2dimethylbutane has been used, together with the preadsorption of n-nonane, to follow the evolution of the porosity, specially the microporosity, upon gasification. Several methods are analyzed in respect to the micropore size distributions of the samples. 113. Pore volume studies on carbon solids P. J. Reucroft, K. B. Pate1 and C. T. Chiou (Department of Metallurgical Engineen’ng and Materials Science, University of Kentucky, Lexington, KY 405%). Pore
volumes, determined by gas and vapor adsorption methods, are often relatively independent of the molecular probe for many activated carbon and graphitic adsorbents. Much greater variations are found when a variety of molecular probes are employed to estimate the pore volume of coal samples. The molecular and surface interactions that are responsible for these effects are discussed. 114. Adsorptionof cyanogen chloride and chloropkrine on activated carbon B. Staginnus ( WWDBW ABC-Schutz, P.O. Box 13 20,
137
D-3042 Munster, Germany). The adsorption rate con-
stants for the adsorption of cyanogen chloride and chloropicrine vapors by packed bed columns of activated charcoal have been studied as a function of volume flow rate. The results allow predictions of breakthrough times of filter canisters in a wide range of volume flow rates. 115. The effect of different methods of actfvatfon on the pososity of active carbons from some agricultural by-products F. Rodriguez-Reinsos, J. de D. L6pez-GonzBlez, A. Linares-Solano and M. Molina-Sabio (Department of Inorganic Chemistry, University of Granada, Granada, Spain). A large number of granular activated carbons has
been prepared from some agricultural by-products using single (CO,) and multistage (air,CO*) activation, as compared with conventional carbonization (N2) followed by CO2 activation. The characterization of all samples has been carried out by adsorption of gases (N2, CO*, nC4HIO) and adsorption from solution (p-nitrohenol, methylene blue, orange II, crystal violet and Victoria blue). For the same yield or percentage burn-off of activated carbon the reaction with air followed by activation with CO* produces carbons with better adsorptive properties. 116. The adsorption of low boiling point gases by activated charcoal cloth A. Capon, B. R. Alves, M. E. Smith and M. P. White (Chemical Defence Establishment, Porton Down, Salisbury, Wiltshire, England). The physical adsorption oi
organic vapours on charcoal cloth is well characterised. Results are presented giving data on the adsorption of chemisorbed gases by charcoal cloth specially treated with chemical impregnants. These impregnants may be introduced either before or after carbonisation and activation of the viscose rayon cloth precursor. 117. High temperature adsorption in relation to porosity of carbons and polarizability of adsorbate A. M. Youssef (Chemistry Department, Faculty of Science, Mansoura University, Mansoura, Egypt). The adsorption of some normal paraffins and cycloparaffins on microporous, mesoporous and nonporous carbon was measured at high temperatures using a micro-chromatographic technique. A relation between the adsorption and the polarizability of the adsorbate was found. Outgassing at high temperatures suppresses the role of polarizability, particularly for nonporous carbons. 118. Formation and structure of active carbons from anisotropk cokes H. Marsh and D. Crawford (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle, Newcastle upon Tyne, NE1 7RU, England) and T. M. O’Grady and A. Wennerberg (Standard Oil Company (Indiana), AMOCO Research Center, P.O. Box 400, Naperville, IL 60540). Active carbons of surface area in
excess of 2000 m*g-’ are available industrially and prepared by the interaction of carbons with KOH at elevated temperatures. The adsorptive properties of these
138
Abstracts
carbons have been examined. The shape and size of supermicroporosity which is responsible for the high effective surface areas of these carbons is resolved using high resolution transmission electron microscopy. 119. The preparation and properties of charcoals used in gunpowder E. McAuliffe, J. R. Lander and H. Marsh (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle, Newcastle upon Tyne, NE1 7RU, England). Charcoals were prepared in the laboratory under known carbonization conditions from hard and soft woods. The charcoals were studied by elemental analysis, adsorption of carbon dioxide at 195K, Hg porosimetry, DGA and ignition temperature measurements. The properties of the charcoals were compared and related to their performance in gunpowder. The charcoal giving evenly burning gunpowder had the highest internal pore volume. 120. Development of a non-destructive test for charcoal beds
M. E. Smith and A. Bailey (Chemical Defence Establishment, Porton Down, Salisbury, Wilts, England). Development of a non-destructive test for determining residual filter life is described; results for the dry air/dry charcoal system are given. Rate constants for various grain size charcoals, correlation between non-destructive and destructive testing and the relationship between non-destructive test penetration and loading on the charcoal are given. 121. Surface and catalytic properties of some metal/carbon catalysts A. M. Youssef and A. I. Ahmed (Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, Egypt). Steam activated and zinc chlorideactivated date pits charcoals were used as supports for some transition metals. The prepared catalysts were used for the dehydrogenation of cyclohexane and for the conversion of isopropanol. The activity and selectivity were found dependent on the pore structure, experimental conditions and the electron configuration of the dorbital. 122. Carbon as a catalyst in oxidation reactions R. Kurth, B. Tereczki and H. P. Boehm (Institut fur Anorganische Chemie der Universitat Munchen, Meiserstrasse 1, D-8ooO Munchen 2, Germany). Catalysis by carbons of the oxidation with O2 of dilute sulfurous acid and of oxalic acid was studied. There are wide variations in the catalytic activities of various carbons. Surface treatment has a profound effect on the activity. Highly active catalysts were obtained by treatment with NH, at 600 to 900°C. The binding of the nitrogen onto the carbon was studied by means of XPS. 123. The applicationof benzene and nitrogen T-curves on grapbitised vulcan 3 to tbe structure of activated carbons G. P. Libberton, K. Graham and J. Dollimore (Uni-
versity of Salford, Salford, England). The surface inhomogeneity of a series of steam activated coal based carbons was investigated using the t-plot technique with particular reference to less than monolayer coverage. The problems associated with the technique are critically examined with respect to micropore value and mesopore surface area calculations. 124. Characteristic isotherms and energy distribution functions for adsorptionon activated carbon A. L. Myers and Di-Yi Ou (Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA 19104). A theory for predicting adsorption from pure vapors on activated carbon has been developed. It is shown that the dimensionless group mRT In (P/PO/AC) is a universal function of 0 (fractional filling of micropores) related to the energy distribution function of the solid. The constants are saturation pressure of adsorbate (PO), adsorption capacity (m) and free energy of immersion (AG). The theory was found to give excellent agreement with experimental data for different types of adsorbates. 125. The influence of sulpbur surface complexes of actfvated carbons on tbe adsorption of He ions from aqueous solution J. de D. Lopez-Gonzalez, C. Moreno-Castilla, A. Guerrero and F. Rodriguez-Reinoso (Department of borganic Chemistry, University of Granada, Granada, Spain). Three commercial activated carbons with different percentages of oxygen surface complexes have been treated with CS2 to introduce C-S complexes on their surfaces. To study the nature of the sulphur groups introduced, the samples were used as catalysts in the decomposition of NaN2 by iodine. The samples have been used as adsorbents of He in aqueous solution, the best treatments being the reaction with H202 followed by reaction with CS2. The increase in pH from 1 to 7 induces a considerable increase in the adsorption of HgZ+. 126. Adsorptionof anions on activated carbon H. Yoshida and K. Kamegawa (Government Industrial Research Institute, Kyushu, Tosu-shi, Saga-ken 841, Japan). It was found that heavy metal ions were effectively adsorbed on activated carbon in the form of complex anion or 0x0 anion in an acidic solution. Halogenide ion was also adsorbed on activated carbon in the acidic region and the atomic ratio of adsorbed halogenide ion to adsorbed hydrogen ion, X-/H’, was approx. 1.0. From these results, it is considered that anions are adsorbed on the positive sites of activated carbon formed by the reaction of basic surface oxides with acids. 127. Silver depositinn on carbon blacks P. Ehrburger, J. Dentzer and J. Lahaye (Centre de Recherches sur la Physico-Chimie des Surfaces Solides, 24, avenue du President Kennedy 62800 Mulhouse, France). Silver has been deposited on carbon blacks by ionic exchange with the cations Ag+ and Ag(NH&. The cation Ag+ is mainly fixed by the carboxylic groups
Both factors exerted their influence below 500°C. Neither factor significantly affected the open micropore volume developed in the chars. 110. Effect of pyrolysis conditions on subsequent gasification of low-temperature lignocellufosic chars D. M. Mackay and P. V. Roberts (Department of Civil Engineering, Stanford
University, Stanford,
CA 94305).
Chars, prepared by pyrolysis of prune pits at I or lS”C/min to 500, 700 or 9OO”C, were subsequently gasified by CO, at 900°C. Pyrolysis conditions did not significantly affect the porosity developed for a given mass loss due specifically to gasification reactions, i.e. excluding additional pyrolytic losses. 111. Porous structure of active carbons and adsorption kinetks A. M. Volochtchouk, M. M. Dubinin and V. A. Gordeeva (Institute of Physical Chemistry of the USSR Academy of Sciences, 117312, Moscow,
U.S.S.R.). New
experimental results on the kinetics of adsorption by microporous active carbons are analyzed using homogeneous and biporous adsorbent models. For some adsorption systems neither homogeneous nor biporous models describe the experimental data obtained properly. Modified biporous model of microporous adsorbents and conditions of the applying of the homogeneous and biporous models of adsorbents are considered. 112. Molecular probe adsorption analysis of actfvated carbons A. Linares-Solano, J. de Lbpez-GonzBlez, J. M. Martin-Martinez and F. Rodriguez-Reinoso (Department of Inorganic Chemistry, University of Granada, Granada, Spain). Two activated carbons, prepared from olive
stones and almond shells, have been reacted with air at 350°C to obtain carbons with a large range of porosity. The adsorption of nitrogen, carbon dioxide, n-butane, benzene, cyclohexane, n-hexane, iso-octane and 2,2dimethylbutane has been used, together with the preadsorption of n-nonane, to follow the evolution of the porosity, specially the microporosity, upon gasification. Several methods are analyzed in respect to the micropore size distributions of the samples. 113. Pore volume studies on carbon solids P. J. Reucroft, K. B. Pate1 and C. T. Chiou (Department of Metallurgical Engineen’ng and Materials Science, University of Kentucky, Lexington, KY 405%). Pore
volumes, determined by gas and vapor adsorption methods, are often relatively independent of the molecular probe for many activated carbon and graphitic adsorbents. Much greater variations are found when a variety of molecular probes are employed to estimate the pore volume of coal samples. The molecular and surface interactions that are responsible for these effects are discussed. 114. Adsorptionof cyanogen chloride and chloropkrine on activated carbon B. Staginnus ( WWDBW ABC-Schutz, P.O. Box 13 20,
137
D-3042 Munster, Germany). The adsorption rate con-
stants for the adsorption of cyanogen chloride and chloropicrine vapors by packed bed columns of activated charcoal have been studied as a function of volume flow rate. The results allow predictions of breakthrough times of filter canisters in a wide range of volume flow rates. 115. The effect of different methods of actfvatfon on the pososity of active carbons from some agricultural by-products F. Rodriguez-Reinsos, J. de D. L6pez-GonzBlez, A. Linares-Solano and M. Molina-Sabio (Department of Inorganic Chemistry, University of Granada, Granada, Spain). A large number of granular activated carbons has
been prepared from some agricultural by-products using single (CO,) and multistage (air,CO*) activation, as compared with conventional carbonization (N2) followed by CO2 activation. The characterization of all samples has been carried out by adsorption of gases (N2, CO*, nC4HIO) and adsorption from solution (p-nitrohenol, methylene blue, orange II, crystal violet and Victoria blue). For the same yield or percentage burn-off of activated carbon the reaction with air followed by activation with CO* produces carbons with better adsorptive properties. 116. The adsorption of low boiling point gases by activated charcoal cloth A. Capon, B. R. Alves, M. E. Smith and M. P. White (Chemical Defence Establishment, Porton Down, Salisbury, Wiltshire, England). The physical adsorption oi
organic vapours on charcoal cloth is well characterised. Results are presented giving data on the adsorption of chemisorbed gases by charcoal cloth specially treated with chemical impregnants. These impregnants may be introduced either before or after carbonisation and activation of the viscose rayon cloth precursor. 117. High temperature adsorption in relation to porosity of carbons and polarizability of adsorbate A. M. Youssef (Chemistry Department, Faculty of Science, Mansoura University, Mansoura, Egypt). The adsorption of some normal paraffins and cycloparaffins on microporous, mesoporous and nonporous carbon was measured at high temperatures using a micro-chromatographic technique. A relation between the adsorption and the polarizability of the adsorbate was found. Outgassing at high temperatures suppresses the role of polarizability, particularly for nonporous carbons. 118. Formation and structure of active carbons from anisotropk cokes H. Marsh and D. Crawford (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle, Newcastle upon Tyne, NE1 7RU, England) and T. M. O’Grady and A. Wennerberg (Standard Oil Company (Indiana), AMOCO Research Center, P.O. Box 400, Naperville, IL 60540). Active carbons of surface area in
excess of 2000 m*g-’ are available industrially and prepared by the interaction of carbons with KOH at elevated temperatures. The adsorptive properties of these
138
Abstracts
carbons have been examined. The shape and size of supermicroporosity which is responsible for the high effective surface areas of these carbons is resolved using high resolution transmission electron microscopy. 119. The preparation and properties of charcoals used in gunpowder E. McAuliffe, J. R. Lander and H. Marsh (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle, Newcastle upon Tyne, NE1 7RU, England). Charcoals were prepared in the laboratory under known carbonization conditions from hard and soft woods. The charcoals were studied by elemental analysis, adsorption of carbon dioxide at 195K, Hg porosimetry, DGA and ignition temperature measurements. The properties of the charcoals were compared and related to their performance in gunpowder. The charcoal giving evenly burning gunpowder had the highest internal pore volume. 120. Development of a non-destructive test for charcoal beds
M. E. Smith and A. Bailey (Chemical Defence Establishment, Porton Down, Salisbury, Wilts, England). Development of a non-destructive test for determining residual filter life is described; results for the dry air/dry charcoal system are given. Rate constants for various grain size charcoals, correlation between non-destructive and destructive testing and the relationship between non-destructive test penetration and loading on the charcoal are given. 121. Surface and catalytic properties of some metal/carbon catalysts A. M. Youssef and A. I. Ahmed (Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, Egypt). Steam activated and zinc chlorideactivated date pits charcoals were used as supports for some transition metals. The prepared catalysts were used for the dehydrogenation of cyclohexane and for the conversion of isopropanol. The activity and selectivity were found dependent on the pore structure, experimental conditions and the electron configuration of the dorbital. 122. Carbon as a catalyst in oxidation reactions R. Kurth, B. Tereczki and H. P. Boehm (Institut fur Anorganische Chemie der Universitat Munchen, Meiserstrasse 1, D-8ooO Munchen 2, Germany). Catalysis by carbons of the oxidation with O2 of dilute sulfurous acid and of oxalic acid was studied. There are wide variations in the catalytic activities of various carbons. Surface treatment has a profound effect on the activity. Highly active catalysts were obtained by treatment with NH, at 600 to 900°C. The binding of the nitrogen onto the carbon was studied by means of XPS. 123. The applicationof benzene and nitrogen T-curves on grapbitised vulcan 3 to tbe structure of activated carbons G. P. Libberton, K. Graham and J. Dollimore (Uni-
versity of Salford, Salford, England). The surface inhomogeneity of a series of steam activated coal based carbons was investigated using the t-plot technique with particular reference to less than monolayer coverage. The problems associated with the technique are critically examined with respect to micropore value and mesopore surface area calculations. 124. Characteristic isotherms and energy distribution functions for adsorptionon activated carbon A. L. Myers and Di-Yi Ou (Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA 19104). A theory for predicting adsorption from pure vapors on activated carbon has been developed. It is shown that the dimensionless group mRT In (P/PO/AC) is a universal function of 0 (fractional filling of micropores) related to the energy distribution function of the solid. The constants are saturation pressure of adsorbate (PO), adsorption capacity (m) and free energy of immersion (AG). The theory was found to give excellent agreement with experimental data for different types of adsorbates. 125. The influence of sulpbur surface complexes of actfvated carbons on tbe adsorption of He ions from aqueous solution J. de D. Lopez-Gonzalez, C. Moreno-Castilla, A. Guerrero and F. Rodriguez-Reinoso (Department of borganic Chemistry, University of Granada, Granada, Spain). Three commercial activated carbons with different percentages of oxygen surface complexes have been treated with CS2 to introduce C-S complexes on their surfaces. To study the nature of the sulphur groups introduced, the samples were used as catalysts in the decomposition of NaN2 by iodine. The samples have been used as adsorbents of He in aqueous solution, the best treatments being the reaction with H202 followed by reaction with CS2. The increase in pH from 1 to 7 induces a considerable increase in the adsorption of HgZ+. 126. Adsorptionof anions on activated carbon H. Yoshida and K. Kamegawa (Government Industrial Research Institute, Kyushu, Tosu-shi, Saga-ken 841, Japan). It was found that heavy metal ions were effectively adsorbed on activated carbon in the form of complex anion or 0x0 anion in an acidic solution. Halogenide ion was also adsorbed on activated carbon in the acidic region and the atomic ratio of adsorbed halogenide ion to adsorbed hydrogen ion, X-/H’, was approx. 1.0. From these results, it is considered that anions are adsorbed on the positive sites of activated carbon formed by the reaction of basic surface oxides with acids. 127. Silver depositinn on carbon blacks P. Ehrburger, J. Dentzer and J. Lahaye (Centre de Recherches sur la Physico-Chimie des Surfaces Solides, 24, avenue du President Kennedy 62800 Mulhouse, France). Silver has been deposited on carbon blacks by ionic exchange with the cations Ag+ and Ag(NH&. The cation Ag+ is mainly fixed by the carboxylic groups